The broad program is to define the nature of acquired immunity in tuberculosis. We have developed a non-viable, non-allergenic vaccine against tuberculosis hopefully suitable for use in man. These methods may be applicable for developing other vaccines against other chronic infectious diseases. This material contains ribosomal RNA. To continue our studies on the nature of the labile, immunizing substances found in the RNA fraction prepared from ruptured viable attenuated mycobacteria. To continue studies on the mode of action of these mycobacterial RNA preparations (myc. RNA) in producing immunity against tuberculosis. To continue our studies on the role of the lymphocyte in immunity to tuberculosis and other diseases due to facultative intracellular parasites. To isolate and identify the filterable mycobacterial growth inhibitory substance(s) (MyGIF) produced by lymphocytes obtained from immunized mice which brings about inhibition of growth of virulent tubercle bacilli within macrophages in tissue culture. To determine the relationship of MyGIP to other lymphocyte products. To continue our studies on the role of the granulomatous (macrophage) response in resistance and immunity to experimental tuberculous infection, and we will study the phenomenon of increased susceptibility and increased resistance to tuberculous infection noted in connection with the granulomatous reaction. To continue our studies on the relationship between immunity and hypersensitivity in guinea pigs and mice. To continue our studies on the effect of myc. RNA on the progression of tumors in mice. To continue our studies on the effect of immunosuppressive drugs on immunity and delayed hypersensitivity in tuberculosis. Bibliographic references: Youmans, G.P. 1975. Relation between delayed hypersensitivity and immunity in tuberculosis. Amer. Rev. Resp. Dis. 111: 109-118. Casavant, C.H. and Youmans, G.P. 1975. The adjuvant activity of mycobacterial RNA preparations and synthetic polynucleotides for induction of delayed hypersensitivity to purified protein derivative in guinea pigs. J. Immunol. 114: 1014-1022.